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Infection and Immunity, June 2000, p. 3377-3384, Vol. 68, No. 6
Department of Molecular Biology and
Biochemistry1 and Department of
Biological Sciences,2 Simon Fraser
University, Burnaby, British Columbia, Canada
Received 28 December 1999/Returned for modification 14 February
2000/Accepted 14 March 2000
Invasive lung disease caused by Aspergillus species is
a potentially fatal infection in immunocompromised patients. The
adhesion of Aspergillus fumigatus conidia to proteins in
the basal lamina is thought to be an initial step in the development of
invasive aspergillosis. The purpose of this study was to determine the mechanism of adhesion of A. fumigatus conidiospores to
basal-lamina proteins and to determine whether conidia possess unique
adhesins which allow them to colonize the host. We compared conidia
from different Aspergillus species for the ability to bind
to purified fibronectin and intact basal lamina. Adhesion assays using
immobilized fibronectin or type II pneumocyte-derived basal lamina
showed that A. fumigatus conidia bound significantly better
than those of other Aspergillus species to both fibronectin
and intact basal lamina. Neither desialylation nor complete
deglycosylation of fibronectin decreased the binding of A. fumigatus conidia to fibronectin, suggesting that
oligosaccharides on fibronectin were not involved in conidiospore
binding. Further evidence for this hypothesis came from experiments
using purified fragments of fibronectin; A. fumigatus
conidia preferentially bound to the nonglycosylated 40-kDa fragment
which contains the glycosaminoglycan (GAG) binding domain. Negatively
charged carbohydrates, including dextran sulfate and heparin, as well
as high-ionic-strength buffers, inhibited binding of A. fumigatus conidia to both fibronectin and intact basal lamina,
suggesting that negatively charged carbohydrates on the surface of the
conidium may bind to the GAG binding domain of fibronectin and other
basal-lamina proteins. These data provide evidence for a novel
mechanism of conidial attachment whereby adherence to fibronectin and
other basal-lamina proteins is mediated via negatively charged
carbohydrates on the conidial surface.
0019-9567/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.
Adhesion of Aspergillus Species to
Extracellular Matrix Proteins: Evidence for Involvement of Negatively
Charged Carbohydrates on the Conidial Surface
*
Corresponding author. Mailing address: Department of
Biological Sciences, Simon Fraser University, 8888 University Dr.,
Burnaby, B.C., Canada. Phone: (604) 291-3441. Fax: (604) 291-3496. E-mail: mmoore{at}sfu.ca.
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